Chapter 266: Trauma to the Extremities

Isolated trauma to an extremity with associated vascular injury has nearly a 10% rate of mortality or limb loss.¹ Injuries involving the lower extremities are more common than injuries involving the upper extremities. The two most commonly injured blood vessels are the femoral and popliteal vessels.² Penetrating trauma with early shock from proximal arterial hemorrhage is more likely to lead to mortality. Blunt distal extremity trauma with associated distal vascular injury is more commonly involved in early limb loss and amputations.

Advances in diagnostic imaging³ and surgical management have dramatically reduced the rate of limb loss and disability due to limb ischemia.⁴ The extent of injury to extremity nerves, bones, and soft tissues now determines if the limb can be surgically salvaged. Identifying and detecting which injuries require surgical evaluation and/or imaging are essential skills for emergency physicians.

Gunshot and knife wounds are the two most common causes of penetrating trauma. Stab wounds have a more predictable pattern of injury, making them more straightforward to manage. Gunshot injuries are more difficult to evaluate due to the extent of tissue damage and wider range of patterns of injury. More sophisticated vascular surgical repair techniques of arterial injuries,⁵ advances made during military conflicts, improved imaging, and other factors have led to a decreased rate of limb amputations and limb disability associated with penetrating trauma.⁶

Perform the primary trauma survey, immediate resuscitation, and secondary survey before focusing on injuries to the extremities. Apply direct pressure, pressure dressings, or a tourniquet to any actively bleeding extremity (see chapter 254, "Trauma in Adults," and "Tourniquets"). Do not get distracted or deviate from the initial trauma management because associated injuries to other areas of the body are common with penetrating injuries. After identifying an injury during the secondary survey, thoroughly evaluate the affected extremity for vascular integrity, nerve function, skeletal injury, and soft tissue injury. The rapid evaluation of extremities for associated arterial injury is critically important for the management of these injuries. Note any hard or soft signs of vascular injury (Table 266-1). Use a Doppler flow device to detect a pulse if distal pulses cannot be palpated.

Thoroughly evaluate nerve, tendon, and muscle function during the physical exam (Table 266-2). Pain on palpation or movement of bony structures or obvious deformities suggests an underlying fracture. Note any intra-articular hematomas or other signs of joint injury. Measure soft tissue lacerations and other associated injuries with a tape measure or ruler. Accurately describe injuries to consultants because measurement of the injury may change management in some situations.⁷

ANKLE-BRACHIAL INDEX

In the absence of hard signs, determine the ankle-brachial index for any injured extremity along with the nonaffected extremity for comparison. An ankle-brachial index reading of <0.9 is considered abnormal and is concerning for associated arterial injury. The ankle-brachial index reliably detects occlusive arterial injury with accuracy as high as 95%, but the true sensitivity and specificity have varied in clinical studies.^8,9 Use caution in relying on a normal ankle-brachial index to rule out arterial injury, because it does not detect nonocclusive arterial injuries such as intimal flaps, focal narrowings, small pseudoaneurysms, and arteriovenous fistulas in up to 10% of cases.¹⁰

Diagnosis of associated injuries depends on a complete history and physical exam of the involved extremity. If any hard signs of vascular injury are present, then consult vascular surgery immediately. If there are any soft signs of vascular injury and/or if the ankle-brachial index is <0.9, then order imaging tests to evaluate for associated vascular injuries, or transfer to an institution with vascular care capability (Figure 266-1).

DIFFERENTIAL DIAGNOSIS

The differential diagnosis for injuries associated with penetrating trauma to the extremities includes arterial or venous injury, nerve damage, tendon lacerations, fractures, soft tissue injury, degloving injuries, damage to joint capsule, bullet embolization of artery, or vein and compartment syndrome.¹¹

LABORATORY TESTING

No specific laboratory testing is indicated for isolated penetrating extremity injuries; in certain cases, type and screening and a CBC may be indicated. If the patient has soft signs of vascular injury or an ankle-brachial index <0.9, then obtain a creatinine to determine renal function in patients with risk for preexisting renal disease. Underlying renal insufficiency creates potential for contrast-induced nephropathy when performing CT angiography. See chapter 88, "Acute Kidney Injury" for discussion of radiocontrast-induced nephropathy.

IMAGING

Plain Radiographs

Obtain anteroposterior and lateral radiographs of extremities with suspected fracture, joint injury, or retained bullet or other foreign body fragments. Oblique views may add value if the physician has a strong clinical suspicion of retained foreign body and it is not shown on anteroposterior and lateral views. Obtain radiographs of the joint above and below the site of injury. Evidence of air in the joint or an intra-articular fracture on the radiograph demonstrates that joint involvement has occurred.

There are four types of fracture patterns associated with low-energy gunshots¹² (Figure 266-2). The drill-hole wound track pattern appears in the more porous and lower density cancellous bone. This pattern is most common in the distal femur, pelvis, and proximal humerus. Unicortical fractures appear in the metaphyses of long bones and occur only due to tangential impact with the bone. Comminuted fractures occur most frequently in diaphyseal bone; multiple bone fragments are common. The fourth type of fracture is the distal spiral fracture, and this occurs most commonly in the femur. There is controversy in the literature over whether this fracture is caused by the bullet itself or associated with falls that occur after the gunshot injury is sustained.¹³

For shotgun or blast injuries, obtain radiographs of the extremity and joint distal to the injury in order to detect any pellets that have embedded into the bone, remain in the soft tissues, or have potentially entered into a joint capsule (Figure 266-3).

CT Angiography

CT angiography is the primary diagnostic study for the evaluation of vascular injuries to the extremities.² CT angiography is noninvasive, provides higher resolution images, and is less expensive when compared to catheter angiography. It provides three-dimensional reconstruction with minimal artifact. CT angiography also assists in the evaluation of extravascular injuries such as fractures, foreign objects, or joint involvement.¹⁴ Studies comparing CT angiography to catheter angiography have demonstrated that the CT angiography sensitivity and specificity rates for identifying clinically significant arterial injuries are equivalent to those with conventional catheter angiography.^15,16,17,18 Limitations of CT angiography include scatter artifact interference caused by bullets, poor visualization of tibial vessels, and the inability to perform any therapeutic interventions during the study.

Ultrasonography

Color flow duplex ultrasonography has a sensitivity that ranges from 50% to 100% for evaluating vascular injuries.^19,20 Given this mixed evidence of accuracy, color flow duplex ultrasonography should not be used as the primary diagnostic study to rule out vascular injuries associated with penetrating trauma to extremities.¹⁰

CONTROL OF BLEEDING

Patients with venous trauma can bleed profusely. Control bleeding with direct pressure, pressure dressing, or a tourniquet. Avoid clamping vessels in an attempt to control bleeding, as this risks nerve damage. Nerves are bundled with vascular structures and can be easily damaged by blind clamping or ligation during the initial trauma resuscitation.

ARTERIAL INJURY

Penetrating injuries to the extremities that involve any associated arterial injury are critically important to recognize early. Figure 266-1 outlines the approach to these injuries.

FRACTURES AND JOINT INJURIES

Penetrating trauma can cause joint sepsis and destruction, rapid chondrolysis, and loss of anatomic contours. These can lead to serious long-term consequences, including posttraumatic degenerative arthritis and partial or total loss of flexibility. Treat bone fractures from penetrating trauma as open fractures. Surgically debride the injury and admit the patient for IV antibiotics, such as a cephalosporin plus gentamicin. Synovial joint fluid is an organic acid, which causes lead bullets to become soluble in the joint and can cause systemic lead toxicity.²¹ If a patient has an obvious bony or joint capsule injury, obtain consultation to evaluate the injury.

WOUND MANAGEMENT

Careful wound management is critical to prevent infection after penetrating injuries. The most important component of wound management is irrigation. Copiously irrigate with saline or tap water (500 to 1000 mL) at high pressures (15 to 20 pounds per square inch). Antiseptic solution does not decrease infection rate and may actually be harmful.²²

Heavily contaminated wounds may require more fluid and/or more pressure. If the wound is older than 3 to 4 hours, gently scrub the wound. Despite the importance of irrigation and wound management, there are many other factors that play a role in infection risk and proper healing, including bacterial inoculum, tissue devitalization, blood supply, time to presentation and treatment, presence of foreign bodies, and host immune status.

WOUND CLOSURE

The decision to close associated open wounds depends on the time that has elapsed since the injury and the degree of contamination. If there is minimal contamination and the wound is well irrigated, it can be closed. It is important to arrange close follow-up in 24 to 48 hours in order to check for developing wound infection. Extremity wounds with retained foreign bodies, major tissue destruction, or contamination should be closed after a delay of 72 to 96 hours. Do not routinely administer antibiotics for uncomplicated extremity gunshot and knife wounds because there is an approximately 2% rate of infection in these injuries.²³ However, antibiotics may be beneficial for treating hand injuries, joint or bony involvement, immunocompromised patients, and wounds with significant contamination.²⁴

SOFT TISSUE FOREIGN BODIES

Plain radiographs will detect glass, metal, bone, or gravel. Wood and other organic material may be missed on plain films, and US is better at identifying these objects. CT scanning is the best modality for identifying both radiolucent and opaque foreign bodies. Several factors impact whether the foreign body should be removed. The benefit of exploring the wound and removing the substance must be weighed against the associated damage to surrounding tissues and the increased risk of infection. Organic material is more reactive and has a higher rate of infection than metal or glass. A bullet generally should not be removed unless the bullet has potential to migrate into surrounding vital structures or if it is in the joint capsule.

Hard signs of arterial injury require immediate surgical consultation, and such patients will need further imaging, surgery, and hospital admission. All other patients with penetrating extremity trauma should undergo a period of observation with associated serial examinations to detect any delayed or missed injuries. There is no consensus on the required observation time required, but a minimum of 24 hours is reasonable.¹⁷

Wound healing may be complicated by infections, missed nerve injuries, tendon or joint injuries, delayed vascular injury, and compartment syndrome. Discuss return precautions with patients before discharge. State these precautions as clearly as possible. Recommend that patients return to the ED for increasing pain, numbness, weakness, redness, or pus drainage from the wound site. Ensuring follow-up with the appropriate surgical service, a primary care provider, or the ED is essential, especially in uninsured patients or patients transported long distances from home, as well as for other high-risk populations.

Uninsured, African American, and Latino populations have higher traumatic injury mortality when compared to the general population. Increased mortality has been demonstrated in the uninsured and the nonwhite populations for lower extremity vascular injuries.²⁵ Ensure appropriate follow-up and outline clear return precautions. If reliable follow-up cannot be arranged, then consider a longer period of ED or hospital observation.

• American College of Surgeons: Advanced Trauma Life Support (ATLS^®) Manual, 9th ed. Washington, DC: American College of Surgeons, 2012.

• American College of Emergency Physicians (ACEP): Clinical policy for the initial approach to patients presenting with penetrating extremity trauma. 1999.

• Eastern Association for the Surgery of Trauma (EAST): Evaluation and management of penetrating lower extremity arterial trauma: An Eastern Association for the Surgery of Trauma practice management guideline. 2012.